Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint/idempotent/destructive=false, so 'read-only, runs straight away' earns no credit. The description does add real behavioral context annotations cannot: it spells out the exact return shape, explains extra_caps semantics, and — most importantly — discloses that emails and usernames are withheld, which prevents the agent from assuming user PII is retrievable.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loads the purpose, then the return shape, then the filtering constraint — the three things an agent needs in order of importance. The only mild redundancy is the trailing 'read-only, runs straight away' line, which is short enough not to hurt scanability.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description carries the return-value burden and does so by naming each field and flagging the PII exclusion. Remaining gaps are minor: no mention of how the result is paginated or ordered beyond per_page, and no note on total-count reporting.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description goes further by enumerating the accepted role slugs even though the schema's role property has no enum constraint. It does not restate per_page limits, but the schema already documents defaults and maximums.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('List site users') and immediately enumerates the returned fields, so the agent knows exactly what data comes back. It never explicitly names wp_get_user as the single-user alternative in the description body — that distinction only appears in the schema's role parameter text, so sibling differentiation isn't self-contained.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It gives useful context by listing the valid role slugs (administrator / editor / author / contributor / subscriber, plus custom roles) as the filtering dimension, which implies when the tool is appropriate. It does not say when not to use it or directly route to wp_get_user; the only routing cue lives in the schema, not the description.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.